2. Oriented strand board (OSB), also known as Sterling board (UK & Ireland)
and by the propriety eponym -Aspenite (U.S. & Canada), is an engineered wood
particle board formed by layering strands (flakes) of wood in specific
orientations.
In appearance, it may have a rough and variegated surface with the individual
strips of around 2.5 x 15 cm / 1 x 6 inch, lying unevenly across each other.
It was invented by Armin Elmendorf in California in 1963.
ORIENTED STRAND BOARD
3. •Individual layers can also vary in thickness to give different finished panel
thicknesses.
•The mat is placed in a thermal press to compress the flakes and bond them by heat
activation and curing of the resin that has been coated on the flakes.
•Individual panels are then cut from the mats into finished sizes. Most of the
world's OSB is made in the United States and Canada in large production
facilities.
•The largest production facilities can make over 1,000,000 square feet (93,000
square metres) of OSB per day.
4. MANUFACTURING
• Oriented strand board is manufactured in wide mats from cross-oriented layers
of thin, rectangular wooden strips compressed and bonded together with wax
and synthetic resin adhesives (95% wood, 5% wax and resin).
• The layers are created by shredding the wood into strips, which are shifted
and then oriented on a belt or wire cauls. The mat is made in a forming line.
• Wood strips on the external layers are aligned to the panel's strength axis, while
internal layers are perpendicular.
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8. •The number of layers placed is determined partly by the thickness of the panel.
Individual layers can also vary in thickness to give different finished panel
thicknesses (typically, a 15 cm layer will produce a 15 mm panel thickness).
•The mat is placed in a thermal press to compress the flakes and bond them by
heat activation and curing of the resin that has been coated on the flakes.
Individual panels are then cut from the mats into finished sizes.
9. •Oriented strand board is manufactured in wide mats from cross-oriented layers of
thin, rectangular wooden strips compressed and bonded together with wax and
synthetic resin adhesives (95% wood, 5% wax and resin).
•The resin types typically used include Phenol formaldehyde (PF), melamine
fortified Formaldehyde or isocyanate , all of which are moisture resistant binders.
The layers are created by shredding the wood into strips, which are shifted and then
oriented on a belt or wire cauls.
•The mat is made in a forming line. Wood strips on the external layers are
aligned to the panel's strength axis, while internal layers are perpendicular.
The number of layers placed is determined partly by the thickness of the panel but is
limited by the equipment installed at the manufacturing site.
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11. PROPERTIES
• OSB panels have no internal gaps or voids and are water-resistant,
although they do require additional membranes to achieve impermeability to
water and are not recommended for exterior use.
• The finished product has properties similar to plywood, but is uniform and
cheaper.
• When tested to failure, OSB has a greater load-bearing capacity than milled
wood panels. It has replaced plywood in many environments, especially the
North American structural panel market.
12. •While OSB does not have a continuous grain like a natural wood, it does have an
axis along which its strength is greatest. This can be seen by observing the alignment
of the surface wood chips.
•All wood-based structural use panels can be cut and installed with the same ease
and types of equipment used with solid wood.
•Some manufacturers treat the wood chips with various borate compounds which are
toxic to termites, wood boring beetles, molds and fungi but not mammals in applied
doses.
13. •The resins used to create OSB have raised questions regarding the potential for
OSB to emit volatile organic compounds(VOCs) such as formaldehyde.
•Urea-formaldehyde is more toxic and should be avoided in home use. Phenol-
formaldehyde products are considered to be relatively hazard-free.
•Some newer types of OSB, so-called "New-generation" OSB panels, use
isocyanate resins that do not contain formaldehyde and are considered non-
volatile when cured. Industry trade groups assert that formaldehyde emissions from
North American OSB are "negligible or nonexistent".
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16. Types
Four grades of OSB are defined in terms of their mechanical performance and
relative resistance to moisture:
OSB/1 – General purpose boards and boards for interior fitments (including
furniture) for use in dry conditions
OSB/2 – Load-bearing boards for use in dry conditions
OSB/3 – Load-bearing boards for use in humid conditions
OSB/4 – Heavy-duty load-bearing boards for use in humid conditions
17. USES
•OSB is a material with high mechanical properties that make it particularly suitable
for load-bearing applications in construction.
•The most common uses are as sheathing in walls, flooring, and roof decking.
•OSB also sees some use in furniture production as well.
•For exterior wall applications, panels are available with a radiant- barrier layer
pre-laminated to one side; this eases installation and increases energy performance
of the building envelope. OSB also sees some use in furniture production.
18. Composite wood
Composite wood is a general term for built up ,bonded
products ,consisting either wholly of natural wood, e.g.-
plywood or coreboard, or of wood in combination with
metals, plastics ,etc.
19. Wood materials adhesively bonded….
Range of products…
Used for a number of structural and nonstructural applications in
product lines
Interior and exterior panels
Furniture
Support structures in buildings….
WOOD COMPOSITES
21. • Plywood is a term applied to glued wood construction built of veneers in such a manner
that the grain of each veneer is at right angles to that of the adjacent veneer in the
assembly.
• Outer plies are called faces or back and the centre ply as core.
Advantages:
• Dimensional stability
• Strength distributed in both directions
• No tendency to split
• Can be made in big sizes
• Molded to various shapes
Plywood
22. Trimming, sanding and storage
Conditioning the panels (MC brought to 12%)
Pressing the glued lay up into a panel (7-8 kg per sq cm)
Mixing and spreading the glue or adhesives (by using spreader and scraper)
Drying the veneers
Preparing the veneers, namely faces, cross bands and cores for gluing
23. • Built up product made of wood layers (called laminae), all laid with their
grain parallel, and glued or otherwise fastened together.
• The laminae may vary as to species, number, size, shape and thickness.
• Glued laminated wood construction or the structural material resulting from
glued lamination is called glulam.
Laminated wood
24. • Laminae which may be thin veneers or boards are seasoned with kilns
• Then cut to uniform width and length.
• Laminae are then arranged in the proper order and fed into a glued spreader
which spreads the glue properly.
• Placed on a jig or form for assembling to the required shape.
• Pressure is applied by means of clamps fitted at regular intervals
25. Advantages :
• Dimensional stability
• Complete utilization of available supplies as short lengths are end jointed and
glued to increase length.
• Can be produced in special shapes, such as curved arches, curved boat framing
etc to provide improved strength.
• More effective and versatile application
• Mixed grades and species can be used in the same structural member.
26. • A coreboard is a composite board built up of a core composed of strips of wood
of various dimensions glued together to form a slab, which in turn glued
between veneers with direction of grain of core strips running at right angles to
that of adjacent veneers.
Types
Batten board - not more than 7.5cm
Block board - not more than 2.5cm
Lamin board - not more than 7mm
Coreboard
27. • Sandwich board is a general term for built up boards having a core of light
material, faced on both sides with a relatively thin layer of material having high
strength properties.
• The two thin facings, called skins are usually of strong dense material since they
are the principal load carrying members of sandwich construction.
• Sandwich construction finds application in aircraft components, motor torpedo
boats, table tops, refrigerators, knock-down containers, landing mats etc.
Sandwich boards
28. • Is a sheet of material made from fibres of wood or other ligno-cellulosic
materials.
• The wood is first defibrated or pulped and the fibres are then interfelted into a
mat and consolidated by pressure and heat.
• Used as core material in coreboards and sandwitch boards
• Fibreboards are manufactured in densities ranging from 32 to 1440 kg per cu
m.
Fibre boards
31. Panel product that is made with wood fragments and or other lignocellulosic materials, bonded
with organic binders with the help of one or more agents like heat, pressure, humidity, catalysts etc.
There is great range of particle shapes and sizes used to make particleboards.
Types:
Chipboard -made with chips
Flake board -made with flakes
Shaving board -made with wood shavings
Wafer board -made with wafer
Depending on the density particleboards are classified as:
Low density boards - specific gravity 0.2-0.4
Medium density boards - specific gravity 0.4-0.8
High density boards - specific gravity 0.8-1.2
Particle board
32. • Raw material is converted into chips shavings and flakes etc. and these are
screened to get particles of uniform size.
• These particles are dried to drive off any excess moisture.
• Dried particles are then mixed thoroughly in mechanical mixers with resin
adhesives or any other additives.
• The mix is formed into particle boards by pressing at a suitable temperature and
pressure.
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34.
35. • Incorporation of two or more fibres within a single matrix
• The resulting material is a hybrid composite, often abbreviated to just "hybrid".
• or it may be two resin systems e.g. an interpenetrating network
–Intraply hybrids(within) - Alternate strands of different fibres in a single layer or ply
–Interply hybrid (across) – Different plies of different fibres
Types:
Wood plastic
Natural fibre thermosets- particle board, fibreboard (MDF,HDF, hardboard, cardboard)
Modified ligno cellolosic
Hybridization is a process of incorporating synthetic fibres with that of natural and metallic fibres in
order to yield better strength, stiffness, high strength to weight ratio and other mechanical
properties.
Hybrid composite
